1. Field of the Present Invention
The present invention relates generally to racks and cabinets for supporting computer and other electronic equipment, and, in particular, to air ducts for providing cool air to hot spots in equipment enclosures.
2. Background
Racks, frames, cabinets and the like for supporting computer and other electronic equipment are very well known. Such support apparatus are often partially or fully enclosed, either directly through the use of doors and panels mounted directly thereon, or indirectly by lining several such apparatuses up in a row such that the sides of each rack is immediately adjacent another rack.
As is also well known, the electronic equipment mounted therein tends to generate large amounts of heat that need to be exhausted away from the equipment effectively in order to maintain the equipment in proper operating order or to prevent damage thereto. As equipment becomes more densely packed with electronics, the quantities of heat have continued to increase in recent years, and heat management has become a significant issue confronting today's rack, cabinet, frame and enclosure manufacturers, the manufacturers of the electronic equipment, and the users of such equipment.
A common type of operating environment for racks, frames, cabinets, and the like (hereinafter generally referred to as enclosures) and the equipment mounted therein is known as a “raised floor” system, wherein the enclosures are supported on a heavy-duty mechanical floor that is installed above the actual floor of the room at a given elevation. One significant advantage of this approach is that cables, wires, water pipes, and other utility connections may be routed to and from the enclosures via the space beneath the floor, thereby leaving the top surface of the raised floor clear for locating enclosures and traversal by users. Another significant advantage, however, is that the space beneath the top surface of the raised floor serves as a plenum through which cool air may likewise be distributed to the enclosures. Through open tiles or perforations or ventilations in the tiles comprising the surface of the raised floor, this cool air may be supplied to the enclosures and used to cool the equipment inside.
The supply of cool air to the raised floor plenum, and the disposal of heated air from the electronic equipment, is conventionally handled by the Computer Room Air Conditioner (“CRAC”). Airflow through the plenum and into the enclosures generally relies solely or at least primarily on the air pressure differential as measured between the raised floor plenum and the ambient room. However, active means are often used to push or pull heated air out of the enclosures.
Unfortunately, the use of perforated floor tiles, typically located directly in front of enclosures to try to cause a maximum amount of cool air to be directed into the enclosures and not merely lost to the ambient room, have been found to be insufficient in cooling the equipment within the enclosures to the desired degree. Thus, a number of techniques and devices have been developed in recent years to more efficiently utilize the capabilities of the CRAC and to put the available cool air to the most efficient use possible. Among others, these include the development of the hot aisle/cold aisle strategy that is now well known to those of ordinary skill in the art, as well as improved strategies involving perforated panels, such as those described in the commonly-assigned U.S. patent application Ser. No. 11/548,158, filed Oct. 10, 2006 and entitled “RATIO OF OPEN AREA TO CLOSED AREA IN PANELS FOR ELECTRONIC EQUIPMENT ENCLOSURES,” and also improved external ducting strategies, such as those described in the commonly-assigned U.S. patent application Ser. No. 11/533,362, filed Sep. 19, 2006, and entitled “AIR DIVERTER FOR DIRECTING AIR UPWARDLY IN AN EQUIPMENT ENCLOSURE,” the entirety of each of which is incorporated herein by reference.
However, little effort has been made to this point in developing ducting strategies for the space inside the enclosures. This is believed to have generally gone undeveloped because of the relative lack of space available inside the enclosures for such efforts. Nonetheless, given today's emphasis on improved efficiency in every aspect of the cooling system, a need exists for such a solution.
One exemplary internal ducting strategy, shown in U.S. Pat. No. 6,745,579, utilizes a cavity-type front door with a solid external panel and a perforated internal panel that creates a cooling air duct at the front of an enclosure. Air flows through a portion of a bottom of the enclosure and then through the duct of the cavity-type door. A drawback of this internal ducting structure is that it is difficult to retrofit an existing enclosure with such structure because the enclosure itself must be altered in order to use it. More particularly, the enclosure must be retrofitted with the cavity-type front door, which may not fit within an existing enclosure, and the bottom of the enclosure must be altered so that air is able to flow into the enclosure and through the duct created between the panels of the front door.
In addition, although the cavity-type door of the '579 patent may provide even flow of cool air to the front of an enclosure, it does not provide a means for selectively providing cooling air to portions of the enclosure. Such selective cooling of equipment stored within the enclosure is desirable. Further, because the cavity-type front door has a solid external panel, air from perforated floor panels in front of the enclosure is unable to enter the enclosure. As such, a significant amount of cooling air is blocked.
In addition, in cooling electronic equipment within an enclosure, a common problem that arises is recirculation of hot exhaust air. As used herein, recirculation may be defined as the condition when hot exhaust air, exiting from the rear of the equipment chassis, travels back into the intake (cold) air stream of the equipment chassis. This recirculating hot exhaust air increases the temperature of the intake air which causes the equipment to run at a higher operating temperature. Accordingly, a device that hinders or prevents recirculation within an enclosure is desirable.